This invention is directed generally to couplers which permit a transfer of AC energy between objects which rotate relative to one another and to an antenna capable of operating in two modes. The contactless coupler is more specifically directed to a rotatable contactless signal coupler which couples RF signals between an antenna and an RF signal processor, such as a transmitter or a receiver, in a two-way radio.
A difficulty exists whenever AC energy must be transferred between objects which rotate relative to one another. Sliding contacts are one solution but they have limited life due to wear and may cause electrical noise. Flexible cables are another solution but these limit the rotation and also often cause wear and noise.
The conventional means for coupling signals, in portable two-way radios and pagers, between the antenna and the signal processor has been through the use of a coaxial connector found within the housing of the particular device. Where the antenna is required to rotate relative to the radio a new type of device is needed which is small, inexpensive, efficient, and highly reliable for coupling RF energy to the antenna. This is especially important where the antenna is to be located on a flip portion of a portable two-way radio.
Portable radios operate in varied and adverse locations. The desire for smaller radios has severely limited the available antenna locations and has degraded antenna performance due to its size and placement within the device. For maximum performance the antenna should be as far as possible from the operator. Newer models of the portable radios have been designed with a flip that folds down for talking and folds up for storage in the pocket. The flip portion is a good antenna location and the main case is usually allocated for the radio electronics. The variations in proximity of the antenna to the case and operator is so great that optimizing for any one condition will invariably degrade performance in other equally likely conditions. Therefore, the optimal antenna will be the one most tolerant of the varying conditions.